Design and Controlled for Bridgeless Zeta-Luo Converter for EV Charging

Abstract

Thewidespreadadoptionofelectricvehicles(EVs)hasnecessitatedthedevelopmentofefficientand reliable charging infrastructure. Conventional EV chargers often employ bridge rectifiers, which can lead to significant conduction losses due to the presence of high-voltage diodes. To address this limitation, a novel EV charger based on a bridgeless (BL) isolated Zeta-Luo converter with built-in power factor (PF) preregulation capability at the supply side has been proposed. The BL isolated Zeta-Luo converter is a combination ofa Zeta converter and aLuo converter, each operating during alternatehalves of the supply voltage cycle. This approach eliminates the need for bridge rectifiers, reducing conduction losses and improving overall efficiency. Additionally, the shared output inductors of the Zeta and Luo converters furthercontributeto the compact sizeand lightweight design ofthecharger.Thebuilt-in PFPreregulation capability ensures that the charger operates with a near-unity power factor, minimizing reactive power consumption and improving grid stability. This is achieved by regulating the input current waveform to closely match the input voltage waveform. The proposed EV charger offers several advantages over conventional chargers, including: The BL topology and shared output inductors significantly reduce semiconductor losses, leading to improved efficiency. The built-in PF Preregulation capability ensures near-unity power factor operation, minimizing reactive power consumption and improving grid stability. The elimination of bridge rectifiers and the sharing of output inductors result in a compact and lightweight charger design. Enhanced performance under sudden voltage variations: The proposed charger exhibits robust performance under sudden line voltage fluctuations, ensuring reliable EV charging even during unstable grid conditions. The Bridgeless Isolated Zeta–Luo Converter-Based EV Charger With PF Preregulation presents a promising solutionforefficientandreliableEVcharging.Itscombinationofhighefficiency,improvedpowerfactor, reduced size, and enhanced performance under voltage variations makes it an attractive choice for future EV charging infrastructure.

Introduction

ZETA Converter:

• The ZETA converter is similar to the SEPIC topology, providing a regulated output voltage from an input voltage that can be above or below the output.

• It uses two inductors and a flying capacitor, but differs by using a buck controller driving a high-side PMOS FET.

• It offers benefits like lower output voltage ripple and easier compensation compared to SEPIC but requires a larger flying capacitor and a specialized buck controller.

• Operates in continuous conduction mode (CCM) with two distinct modes depending on the switch state, storing and transferring energy via coupled inductors and capacitors.

Luo Converter (Boost Converter):

• The Luo converter is an isolated DC-DC converter favored for high-power applications due to high efficiency, high voltage gain, continuous input current, and low ripple.

• Developed from the Super Lift Luo topology, it overcomes drawbacks of traditional boost and buck-boost converters, such as low gain, high ripple, and non-isolated output.

• Uses two inductors and capacitors in a two-mode operation controlled by a switch, managing energy transfer efficiently.

• Inductor and capacitor selection is critical to minimize ripple and ensure fast, stable voltage response.

Two-Stage Bridgeless Isolated Zeta–Luo Converter for EV Charging:

• Combines a power factor preregulation stage (boost or Vienna rectifier) with a bridgeless isolated Zeta–Luo converter stage.

• This topology provides high efficiency, wide input voltage range, low output voltage ripple, and sinusoidal current draw from the AC mains.

• Suitable for electric vehicle (EV) charging applications, offering improved performance compared to conventional chargers.

Additional Insights:

• The text includes a literature review highlighting recent trends in power electronics for EV chargers, focusing on efficiency, power factor correction, and converter topologies.

• Research shows the effectiveness of fuzzy logic control in maintaining stable output voltages under varying input and load conditions.

• Overall, the design approach favors low component stress to enhance efficiency, reduce size, and lower cost.

Conclusion

Theworkcarriedoutinthereportcanbesummarizedbrieflyasfollows.AnimprovedPQbasedBLisolatedZetaLuoconverterhadbeendesignedinDCMforthe EV battery charger. This configuration was achieved with combined Zeta and Luo converters, whichweredesignedtoworkduringindividualhalvesofsupplyvoltage.Thisgivesanadditionalbenefitofhigherefficiencythanthepreviouslydevelopedconvertersonaccountofsharingoutput inductors for both converters. Therefore, the charger cost and size were reduced. Moreover, a uniform charging current was obtained for the battery due to the presence of an output inductance in both converters, as compared to the Zeta or Luo converter was used for both cycles. Similar pulses were applied to both devices during UPF operation; therefore, the gate drive and control implementation were easy. TheperformanceofthischargerwasrecordedasperanIEC61000-3-2standardguidelines, over the entire operating range of line and loadings. The line current was reshaped to sinusoidal and unity PF was achieved for a complete range of mains voltage. The source current distortion wasmeasuredaslowas4.1%,3.4%,and4.3%duringCCchargingand7.1%duringtheCVmode. Therefore, this PF preregulation-based BL isolated converter seemed to be an improved solution for commercially cost effective off-board charging. The BL topology and shared output inductors significantly reduce semiconductor losses, leadingtoimprovedefficiency.Thebuilt-inPFPreregulationcapabilityensuresnear-unitypower factor operation, minimizing reactive power consumption and improving grid stability. The elimination of bridge rectifiers and the sharing of output inductors result in a compact and lightweightchargerdesign.Enhancedperformanceundersuddenvoltagevariations:Theproposed charger exhibits robust performance under sudden line voltage fluctuations, ensuring reliable EV charging even during unstable grid conditions. The Bridgeless Isolated Zeta–Luo Converter-Based EV Charger With PF Preregulation presents a promising solution for efficient and reliable EV charging. Its combination of high efficiency, improved power factor, reduced size, and enhanced performance under voltage variations makes it an attractive choice for future EV charging infrastructure.

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Copyright

Copyright © 2025 Vishal Kardak, Roshan Bodke, Chandan Dhake, Umesh Kalyankar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.